vivaldi is not available on the main repo of any arch based system however you can find it in the aur
to install type yaourt -S Vivaldi or (Vivaldi-snapshot)
you can also add herecura repo which has it then you can install it via Pacman
check here how to add it

I'm a pretty dedicated Kubuntu man, myself. Yeah, I know it has some issues, the criticisms are valid, but somehow it still checks the boxes for me anyway. I do replace the generic Ubuntu kernel with the liquorix one, and you'd probably weep if you saw the number of PPAs in my apt sources.list, but when all is said and done it's still miles beyond what I put up with from Windows 10.

Vivaldi runs marvelously on it, but I just got the KDE Plasma bump to...goes to check version 5.11.95 which brings the one button, vertical application menu philosophy to the whole system! The only bummer is that Vivaldi doesn't recognize it and still makes its own button in the Tab Bar. Wouldn't it be the coolest thing ever if Vivaldi's menu just popped up into the Title Bar like all the native KDE apps?

I do also want to tip my hat to those here of tribe Manjaro. I too have spent many months running Manjaro, and to its credit I will say that my venerable ThinkPad T420s that travels everywhere with me never ran faster than it did on Manjaro. It opened my eyes to just how much inefficiency creeps into an operating system with every effort to coddle the user base. The thing that guided me home to Kubuntu was the fact that .deb files are everywhere these days, and I just know it more intimately. When I sell my first startup for tens of millions and retire to someplace cold, desolate and quiet, I keenly anticipate all the time I'll spend becoming as familiar with Manjaro as I am with Kubuntu.

I have both, though snapshot I download manually. Mageia 6 includes both the system updater and some software updater that manages to update Vivaldi stable on its own, no idea how it does that. Firefox updates from the system updater (from Mageia's repositories, but not Vivaldi - but it updates anyway.

@danielson do you have the aur enabled?
if you don't follow this, then try the command again
Edit: does the error say command not found or target not found?
Edit: just noticed you put the v as capital while its small the package does exist

@steffie the unstable branch is pretty stable
I switched to it when plasma 5.11 came out and the stable repo didn't have even after a week, haven't gone back to stable since then and everything works as expected never had any issues with updates and no breaks so far (over 3 months)

@blacksuan19 Hiya, oh that's interesting, ta. Several people in the forum there have tried valiantly to get me to brave-up for at least the Testing repo, even if not all the way to Unstable, but i just remain too lilly-livered for that [i know that i don't have the Linux-smarts to get myself out of trouble if my system did break]. Snapshot for Vivaldi does not scare me at all, but the equivalent for my actual OS quite petrifies me.

Warning: Software downloaded and installed from the testing repositories will by nature not have been fully tested, and may be unstable.
One of the many features that sets Manjaro apart from other Arch-based distributions is that it uses its own dedicated software repositories, rather than relying on those provided by Arch itself. In fact, to ensure continued stability and reliability, Manjaro actually uses three distinct types of software repositories:Unstable repositories: These are used to store software packages that have known or suspected stability and/or compatibility issues. This software may therefore be subject to patching by the Manjaro developers prior to being released to the testing repositories. Although the very latest software will be located here, using the unstable respositories may consequently break your system!Testing repositories: These are used to store patched software packages from the unstable repositories, as well other new software releases that are considered at least sufficiently stable. This software will be subject to further checks by developers and testers for potential bugs and/or stability issues, prior to being released to the stable repositories for public use.Stable repositories: These are the default repositories used by Manjaro systems to provide updates and downloads to the general user base & chicken-sh*t know-nothings like Steffie.

@steffie well, I haven't faced any issues so far
i always thought that testing has newer software than unstable haha just noticed that unstable actually has the newest ( should read the wiki next time)

Mageia, being a fork of the (now defunct) Mandriva Linux, has no particular issues installing software (in RPM format) downloaded to the local drive, so I can (and did in prior versions) just download the RPM package and install it. However, Mageia 6 (the latest version) includes a utility that checks for updates of software not available in Mageia's own repositories. Not sure how they know where to check updates, but it tells me (sometimes a day later) that updates are available and will install them if requested. Yes, it checks both stable and snapshot, but as a Soprano the snapshots I install would not be available to their updater. So I update snapshots manually, but let the software updater take care of stable.